Apparatus for making water drums of water-tube boilers



Feb. 21, 1933. M. uLRxcH 1,398,070

APPARATUS FOR MAKING WATER DRUMS OF WATER TUBE BDILERS Filed NOV. 11, 1930 Patented Feb. 21, 1933 UNITED STATES PATENT OFFICE MAX ULRICH, OF STUTTGART, GERMANY, ASSIGNOR TO THE FIRM VEREINIGTE I STAHLWERKE AKTIENGESELLSCHAFT, OF DUSSELDOBF, GERMANY APPARATUS FOR MAKING WATEE- DRUMS or VZ'ATER-TUBE- BOILERS Application filed November 11, 1930, Serial No. 494,848,- and in Germany November 16, 1929.

There is the great disadvantage in the thickness of the manufacture of water-drums of watertube boilers of corrugated form by pressinginto corrugated form straight tubes of approximately rectangular cross-section by the use of upper and lower dies and by means of guide walls which without leaving gaps support the sides of the tubes that are still straight and between which at least one of the dies slides that, owing to the form of dies hitherto used for this purpose, sharp-edged corners are formed in the finished product between every two faces of the walls that are at right angles to each other. Even in those cases in which the straight blanks are sufii ciently rounded off at the corners, these corners acquire sharp edges during the corrugating process by reason of the straight edges of the dies.

According to my present invention the corrugated surfaces of the upper and lower dies are provided on their longitudinal sides with continuous extensions beak-shaped in crosssection and forming an arch-shaped transition between the working surfaces of the upper and lower dies, and the contact surfaces of the lateral guide walls. These beaklike extensions, which project over the actual pressing faces of the dies only corresponding 1 to the radius to be produced on the blank,

prevent sharp edges being formed when producin the corrugated shape, so that in the completely pressed blanks both the outer radius and the inner radius which in certain circumstances is prescribed can be retained with certainty, and the formation of folds within the blanks is prevented.

As already stated, the invention relates exclusively to means by which the sides of the tubes which are left straight are supported without gaps by guide walls. In other known types of apparatus, in which the sides of the tubes which are left straight are not supported without gaps, there is the risk that the sides of the tubes may be forced out between the dies; furthermore, there are not the same difiiculties in the provision of proj ections on the dies for rounding off the edges of the tubes, as in the apparatus according to the invention, in which the space for the projections to be provided on the movable die is limited by the guide walls, between which the movable die slides, and, in which consequently it is not obvious to provide'thin independent projections on themovable die, especially in the case of the considerable forces which arise in the pressing of water-drums.

One form of the apparatus according to the invention is illustrated by way of example in the accompanying drawing in which:

Figure 1 is a longitudinal section of the apparatus,

Figure 2 is a cross-section through the upper and lower dies (in the latter in the left and right-hand halves of the drawing in two different positions).

Figure 3 is another view of the dies with a water-drum in position between the same shown in cross-section,

Figure 4 is an enlarged fragmentary section of the upper right corner of the drum of Fig. 3, and

Figure 5 is a similar fragmentary view of a corresponding portion of a drum made with dies lacking the features of the present invention.

The upper die 1, which in the construction illustrated, consists of several parts, and the lower die 2, which likewise consists of several parts, are provided on the longitudinal sides of their corrugated working surfaces with projections 3 which are beak-shaped in cross-section, correspondingly corrugated and continuous. The projections 3 form arches connecting the working surfaces of the dies with the abutment surfaces of the lateral guide walls at secured to the lower die and sliding on the upper die during the operation of pressing.

In order to render it unnecessary to change the complete dies or their most important parts, should the projections wear away rapidly, the longitudinal-side pressing surfaces, which are rib-shaped, may according to the invention be formed by special interchangeable parts secured laterally to the middle parts of the dies.

It will, however, be understood that the apparatus according to the invention may be constructed so that a die is integral with the rib-like projections on the two sides.

I claim:

1. Apparatus for manufacturing waterdrums for watertube boilers with corrugated walls from straight tubes approximately rectangular in cross-section by the use of upper and lower dies and guide walls which support without gaps the sides of the tubes, which are left straight, and between which at least one of the dies slides, characterized in that the corrugated surfaces of the upper and lower dies which produce the'corrugated form have on their longitudinal sides continuous projections, beak-shaped in cross-section, which form an arch between the working surfaces of the upper and lower dies and the contact surfaces of lateral guide walls.

2. Apparatus according to claim 1, characterized in that the longitudinal side-pressing faces of the dies provided with the projections that are beak-shaped in cross-section are formed of separate interchangeable parts.

MAX ULRICH. 

